GENETIC DIVERSITY AND HETEROSIS AMONG MAIZE COMMERCIAL HYBRIDS OF JALISCO RELEASED IN THE 1990 DECADE

Abstract

Genetic diversity and specific heterosis. were studied. between maize (Zea mays L.) commercial hybrids released in the 1990 in Jalisco, México, The objectives were to identify good combinations between commercial hybrids and to define heterotic pairs to form inter varietal hybrids in the short term, and also to develop inbred line hybrids in the intermediate and long terms; in addition, to confirm whether crosses between commercial hybrids represent better options to for auto-consumption seed in relation to the use of advanced generations (F₂) of the same hybrids. Nine maize hybrids were considered, divided in two groups of six materials each including three hybrids in common. Hybrids, their crosses and their F₂ generations were evaluated at five environments in Jalisco under rainfed conditions. Genetic diversity (DG), heterosis percentages and heterosis effects, were calculated. DG average values among the maize commercial hybrids were: 0.76 and 0.97 for Group 1 (A-7520, H-357, P-3296, C-220, Tornado and D-801B) and Group 2 (A-7573, H-357, P-3066, C-220, Tornado and D-880). We consider that these values, do not represent risks of genetic vulnerability for grain production in Jalisco State. The average heterosis values for grain production for Group 1 (-9.8 %) and Group 2 (3.1 %) indicate that some crosses are similar in grain yield to their F₁ pairs hybrids. Some combinations between commercial hybrids, such as P-3296 x H-357 and A-7573 x H-357, could be used as heterotic patterns to develop new hybrids. The superiority for grain yield of the crosses among commercial hybrids relative to their F₂ generation was confirmed.